压缩剪切测试中载荷传递行为的数字光弹性研究

Study of Load Transfer in Compression Shear Test based on Digital Photoelasticity

结合光弹性四步彩色相移法,提出改进的六步相移法来计算全场剪应力,对径压缩圆盘实验证实了该方法的正确性,并进一步研究了同质材料连接结构在压缩剪切测试中的层间剪切行为。实验结果表明:全场等色线条纹级数和剪应力连续分布且随载荷而增加;中线附近剪应力趋于零,而条纹级数为峰谷。在连接界面上的条纹级数和剪应力出现峰值,特别是在连接界面端部为最高,在最大载荷下可分别达3.5级和2.4MPa,是导致连接界面脱粘开裂的危险区域。连接结构通过层间剪应力进行应力传递,在连接界面上剪应力与外载基本保持平衡。

An improved six-step phase-shifting method was proposed to calculate the full-field shear stress based on a four-step color phase-shifting method in digital photoelasticity.This method was verified by radial compression of a disk,then further study of interlaminar shear behavior in compressive shear test for connection structure made of homogeneity material was carried out.Experimental results reveal that isochromatic fringe order and shear stress are distributed continuously and increased with compression increasing.However,shear stress goes to zero and isochromatic fringe order decreases to valley-bottom at midline of the specimen.They reach peaks at two compressive shear sections,and especially the maximum values appear at four right-angle edges.It means that the cracking would be happened firstly at those edges.Under the load of 705.6N,the fringe peaks and shear stresses at right-angle edges reach to 3.5 orders and 2.4MPa,respectively.Stress transfer in a connection structure is mainly realized by interlaminar shear,while shear stress is basically balanced with the applied load at connection interface.